The Specific Aim of this Core is to provide two categories of services to the Program Project: 1) flow cytometry and cell sorting methods and technologies, and 2) assays of glutathione and the activity of redox enzymes glutathione-s-transferase, superoxide dismutase (S.O.D.) and catalase. We will also assist investigators in finding the most appropriate ways to apply these techniques to their research objectives and to interpret the experimental results. Cytometry and cell sorting will be essential parts of each of the program projects, providing variety of analytical services and techniques. Assays of DNA content, cell cycle and cell proliferation, a novel cytometric assay of oxidative DNA damage and repair, and cytometric assays related to resistance to oxidative damage (glutathione content, cell viability and apoptosis) will constitute major uses of cytometry in this Program Project proposal. In addition, this core will provide non-cytometric assays that will be widely used in the Program Project: HPLC and spectrophotometric quantitative assays of the important intracellular antioxidant glutathione; assays of glutathione-s- transferase, a principal enzyme responsible for carcinogen detoxification; assays of GSH peroxidase and GSH reductase, important enzymes in the synthesis of glutathione, and assays of the oxygen radial scavenging enzymes superoxide dismutase (S.O.D.) and catalase.